Add mapbox#92 - Generate exact single tile

src/index.js

@@ -5,18 +5,21 @@ import wrap from './wrap.js'; // date line processing
 import transform from './transform.js'; // coordinate transformation
 import createTile from './tile.js'; // final simplified tile generation
 
-const defaultOptions = {
+const defaultTileOptions = {
  maxZoom: 14, // max zoom to preserve detail on
- indexMaxZoom: 5, // max zoom in the tile index
- indexMaxPoints: 100000, // max number of points per tile in the tile index
  tolerance: 3, // simplification tolerance (higher means simpler)
  extent: 4096, // tile extent
  buffer: 64, // tile buffer on each side
- lineMetrics: false, // whether to calculate line metrics
+ lineMetrics: false // whether to calculate line metrics
+};
+
+const defaultOptions = extend(Object.create(defaultTileOptions), {
+ indexMaxZoom: 5, // max zoom in the tile index
+ indexMaxPoints: 100000, // max number of points per tile in the tile index
  promoteId: null, // name of a feature property to be promoted to feature.id
  generateId: false, // whether to generate feature ids. Cannot be used with promoteId
  debug: 0 // logging level (0, 1 or 2)
-};
+});
 
 class GeoJSONVT {
  constructor(data, options) {
@@ -214,3 +217,20 @@ function extend(dest, src) {
 export default function geojsonvt(data, options) {
  return new GeoJSONVT(data, options);
 }
+
+export function geoJSONToTile(data, z, x, y, options, shouldWrap = false, shouldClip = false) {
+ options = extend(Object.create(defaultTileOptions), options);
+
+ let features = convert(data, options);
+ if (shouldWrap) {
+ features = wrap(features, options);
+ }
+ if (shouldClip || options.lineMetrics) {
+ const pow2 = 1 << z;
+ const buffer = options.buffer / options.extent;
+ const left = clip(features, pow2, (x - buffer), (x + 1 + buffer), 0, -1, 2, options);
+ features = clip(left || [], pow2, (y - buffer), (y + 1 + buffer), 1, -1, 2, options);
+ }
+
+ return features ? transform(createTile(features, z, x, y, options), options.extent) : null;
+}